1. Field of the Invention
The present invention relates to a sheet collection apparatus which stacks and houses conveyed sheets.
2. Description of Related Art
As a sheet collection apparatus, for example, a mail collection apparatus which stacks and houses mails conveyed at a relatively high speed in the erected posture is so far known.
This type of mail collection apparatus has a stacking portion, a take-in roller to take in mails that are conveyed to the stacking portion, and a back-up plate to bias mails stacked in the stacking portion in the stacking direction and press mails against the take-in roller.
The stacking portion has a bottom wall to support the lower elongate edges of mails conveyed on the conveying path and pushed in the stacking portion by the take-in roller and a rear wall against which the leading edge of a mail in the conveying direction runs and is stopped there.
A succeeding mail that is conveyed at a high speed is taken in the contact portion between mails at the end of mail away from the back-up plate. When the take-in roller is rotated, the mail is further taken in and the leading edge of the mail runs against the rear wall and is stopped there. Plural mails are thus stacked sequentially in the stacking portion.
However, in the above-mentioned conventional sheet collection apparatus, as the rotating speed of the take-in roller is set at the same speed as the mail conveying speed, the leading edge of mail taken in the stacking portion runs against the rear wall while maintaining a high-speed and the mail was bounced by the shock when the rear wall. As a result, the stacking posture of mails became uneven and a noise problem was caused.
Further, in the above-stated conventional sheet collection apparatus, mails stacked at the end in the conveying direction in the stacking portion are in contact with the take-in roller that is constantly in rotation. Therefore, when the take-in roller is rotated at a high-speed as stated above, there was such a problem that a mail was contaminated on its surface by the friction between the roller surface and the mail surface.
Further, in the case of the conventional sheet collection apparatus, when stacked mails in the stacking portion exceeds a fixed quantity, mass of mails itself becomes a large load, the thrusting force between a mail at the end and the take-in roller becomes large and the take in operation by the take-in roller couldn't carried out properly and the jamming was generated.
Further, in a conventional postal matter collection apparatus, there is provided a guide plate inclined to already stacked mails to guide mails that are conveyed on the conveying path to the contacting portion between already stacked mails and the take in roller.
Mails conveyed on the conveying path are guided along the inclined guide plate and sent to the contacting portion between the take in roller and already stacked mails. Then, these mails are taken in the stacking portion by the rotating take-in roller along the already stacked mails and the rear end of the mails are bumped against the wall and stopped there. In order to orderly stack mails that are taken in next, the guide plate is provided to incline to the mails at the end portion.
However, in the case of such type of apparatus to guide mails along the guide plate provided inclining to the stacked mails at the end portion as the above-mentioned conventional mail collection apparatus, the state of mail changes depending on stiffness of mail being guided. That is, the rear edge of a mail having a relatively large stiffness is properly separated from the guide plate by a large stiffness. But, the rear edge of a mail having a small stiffness is kept attached to the guide plate even when taken in by the take-in roller and a mail that is taken in next could not be stacked orderly and jamming was caused.